From the Guidelines
Cauda equina syndrome is a medical emergency that requires immediate attention, and the imaging study of choice is MRI lumbar spine without IV contrast, as it can accurately depict soft-tissue pathology and assess spinal canal patency. The symptoms of cauda equina syndrome include severe low back pain, sciatica affecting both legs, saddle anesthesia, bladder or bowel dysfunction, and sexual dysfunction 38. The most common cause of cauda equina syndrome is lumbar disc herniation at the L4-L5 and L5-S1 levels, but other etiologies such as neoplasm, infection/inflammation, spinal stenosis, and hemorrhage can also be responsible 1.
Some key points to consider in the evaluation of suspected cauda equina syndrome include:
- Multifocal deficits and progressive neurologic deficits can be caused by noncompressive etiologies with overlapping clinical features 1
- A prospective cohort study by Bell et al recommends urgent MRI assessment in all patients who present with new-onset urinary symptoms in the context of low back pain or sciatica 1
- A single 3-D heavily T2-weighted fat-saturated sequence protocol has been shown to be a rapid and highly sensitive tool for evaluating cauda equina syndrome in the emergency department 1
The use of MRI lumbar spine without IV contrast is preferred because it can accurately depict soft-tissue pathology, assess vertebral marrow, and assess spinal canal patency 1. However, CT lumbar spine without IV contrast can also be used to answer the question of whether or not cauda equina compression is present, and CT myelography of the lumbar spine can be useful for surgical planning in patients with cauda equina syndrome 1.
In terms of treatment, emergency surgical decompression is typically necessary to relieve pressure on the nerve roots, and ideally should be performed within 24-48 hours of symptom onset to maximize chances of recovery. The prognosis depends on the severity and duration of compression before treatment, with better outcomes associated with earlier intervention.
From the Research
Definition and Causes of Cauda Equina
- Cauda equina syndrome is an uncommon but serious cause of lower back pain resulting from compression of the cauda equina nerve roots, most commonly by lumbar disc herniation 2.
- It is a rare condition that affects the nerves in the spine supplying the bladder, bowel, and sexual function 3.
- Cauda equina syndrome can result in severe morbidity and can be due to a variety of causes, most commonly vertebral disc protrusion 4.
Symptoms and Diagnosis
- Red flag symptoms, such as bladder dysfunction, saddle anesthesia, and sciatica, should lead to high clinical suspicion of cauda equina syndrome 2.
- Bilateral neurogenic sciatica, reduced perineal sensation, altered bladder function leading to painless urinary retention, loss of anal tone, and loss of sexual function are findings consistent with cauda equina syndrome 4.
- Diagnosis typically involves magnetic resonance imaging (MRI) or computed tomography myelography if MRI is not available 4.
- Postvoid bladder volume assessments can assist in the evaluation of cauda equina syndrome 4.
Treatment and Management
- Urgent decompressive surgery is usually recommended for the best outcomes, to reduce morbidity and complication rates 2.
- Treatment relies upon surgical consultation and operative intervention for decompression 4.
- Immediate magnetic resonance imaging, within 1 hour of presentation to the emergency department, is crucial in patients with suspected cauda equina syndrome to allow prompt diagnosis and treatment 2.
- Timely, effective diagnosis and management of patients with cauda equina syndrome results in a better outcome 3.
Incidence and Prognosis
- Cauda equina syndrome occurs in 2.8% of decompressions for spinal stenosis 5.
- Delays in diagnosis can have devastating and life-changing consequences for patients and result in high-cost negligence claims 3.
- All patients who developed cauda equina syndrome improved over 3 to 9 months, but none completely resolved 5.